As a method for peeling off an asphalt layer paved on a base of a concrete slab which is generally non-electric conductive during a repair work of an asphalt-paved road or the like, a method of peeling off the asphalt layer from the concrete slab by a cutting machine is commonly used. However, when such method is used, a concrete slab which is not intended to be cut is cut by the cutting machine, and the concrete slab becomes thinner each time the asphalt layer is a peeled off during the repair work. In addition, microcracks may be made on the cut concrete slab due to impact thereon by the cutting machine, which deteriorates the concrete slab by corrosion, salt damage, freeze or the like of reinforcing steels in the concrete slab because of water entry, such as rain water, into the microcracks. Moreover, since problems of large vibration and/or noise are generated during the work, and the operation efficiency is extremely low, the application is limited to small-scale repair works.
With respect to a technique of peeling an asphalt layer paved on a steel plate deck of a bridge or the like, a removing method and apparatus as disclosed in Japanese Patent Number 4330639 are proposed. In the technique disclosed in Japanese Patent Number 4330639, the steel deck plate is subjected to electromagnetic induction heating to soften a part of the asphalt layer, and the softened layer is peeled off from the steel deck plate to peel of the asphalt layer. According to this technique, the asphalt layer can be peeled off from the steel deck plate without scratching the steel deck plate or making large vibration and/or noise.
Japanese Patent Application Publication No. 2013-142252 proposes a construction method of block pavement using heat based on electromagnetic induction. In this technique, a thermoplastic material and metal material are blended or laid in a bed mortal or on its surface which is to be laid on a base layer, and after paving blocks are laid and arranged on the bed mortal, electromagnetic induction is given from above the paving block so that the metal material is heated to soften the thermoplastic material, and the paving blocks are securely crimped to the bed mortal and located at predetermined positions. The softened thermoplastic material hardens during a process of returning to room temperature, and thus, the bed mortal and the paving blocks are integrated.
Japanese Patent Application Publication: No. JP H07-179828A discloses an adhesive sheet which is easily peeled from an adherend, and a method for peeling off the adhesive sheet. In this technique, the adhesive sheet is configured by a thermal adhesive layer using natural or petroleum asphalt, a heat generating layer laminated thereon, and a substrate layer laminated further thereon.